This invention relates to a combined differential gear device in which a planetary gear mechanism and a differential gear mechanism are incorporated in a housing.
A four-wheel drive vehicle having a front transverse engine includes a front differential gear device connected to a front accelerator shaft, a rear differential gear device connected to a rear accelerator shaft, and a sort of coupling for transmitting power from a transmission to the front and rear differential gear devices and absorbing differential rotation between the front and rear differential gear devices. A center differential gear device is a desirable means for normally distributing power to the front differential gear device and to the rear differential gear device. However, the four-wheel drive vehicle having the front transverse engine occasionally does not have a space enough to install a one-input two-output mechanism which is necessary for the center differential gear device.
U.S. Pat. No. 5,484,348 discloses a combined differential gear device in which a differential gear mechanism and a planetary gear mechanism are incorporated in a housing. In case this combined differential gear device is applied to a four-wheel drive vehicle having a front transverse engine, the differential gear mechanism is used as a center differential gear device and the planetary gear mechanism is used as a front differential gear device. Therefore, this combined differential gear device can considerably solve the differential gear device and the front differential gear device, another problem is arisen in which the manufacturing cost is increased.
An object of the present invention is to provide a combined differential gear device in which a large chamfering can be formed on a housing.
In order to achieve this object, a first mode of the present invention relates to a combined differential gear device including a hollow housing which is rotation-driven about a rotation axis, and a planetary gear mechanism and a differential gear mechanism which are disposed within the housing, wherein
the planetary gear mechanism includes an inner gear rotatably disposed within the housing with an axis thereof aligned with the rotation axis, a sun gear rotatably disposed within the housing with an axis thereof aligned with the rotation axis and with at least a part thereof inserted in the inner gear, and a planetary gear disposed within the housing such that the planetary gear is rotatable about its own axis, the planetary gear being capable of revolving about the rotation axis together with the housing and engaged with the inner gear and the sun gear, at least a part of the sun gear inserted in the inner gear being provided with a hollow portion, and wherein
the differential gear mechanism includes a hollow casing rotatably disposed within the sun gear about the rotation axis and connected to the inner gear so as to be rotated in unison with the inner gear, an element gear disposed within the casing such that the element gear is rotatable about its own axis, the element gear being capable of revolving about the rotation axis together with the casing, and a pair of side gears rotatably disposed within the casing with axes thereof aligned with the rotation axis and engaged with the element gear. above-mentioned problem in that there is no space enough to install the center differential gear device.
Requirements for an arrangement of a front differential gear device in a front-wheel drive vehicle having a front transverse engine are; height from the ground surface, position in a forward/backward direction for achieving reduction of the overhang weight and an arrangement in a left/right direction between two accelerator shafts. In order to satisfy those requirements as much as possible, a large external chamfering is formed on the housing of the front differential gear device. This large external chamfering is placed in opposing relation to a similar chamfering of a torque converter or clutch. This requirement must also be satisfied in order to accomplish a four-wheel drive vehicle by installing a combined differential gear device in a space for the front differential gear device.
However, the differential gear mechanism of the combined differential gear device disclosed in the above-mentioned U.S. Pat. No. 5,484,348 has a pair of side gears arranged on a rotation axis of a housing. A planetary gear mechanism is disposed within one of the side gears. So, this side gear has a comparatively large diameter. The other side gear also has a large diameter corresponding to the diameter of the first-mentioned side gear. The two side gears, each having a large diameter, are arranged side by side in an axial direction of the housing. Moreover, a pair of planetary gears to be engaged with the corresponding side gears are arranged on an outer periphery side thereof. Unless a large number of such planetary gears are arranged in the circumferential direction, it becomes necessary, in order to obtain a sufficient strength, to increase the tooth-width of each side gear and thus, to increase the tooth-width of each planetary gear. This results in a problem that a large chamfering is difficult to be formed on the housing. Moreover, since a large number of planetary gears become necessary to be used on both the center
In the first mode of the present invention, it is accepted that the planetary gear is rotatably received in a pocket formed in the housing or the planetary gear is rotatably supported on the housing through a shaft. Preferably, bevel gears are used as the element gear and as the side gear, and the element gear is arranged with an axis thereof orthogonal to the rotation axis. It is also preferred that a tapered chamfering is formed on one end portion of the housing.
A second mode of the present invention relates to a combined differential gear device including a hollow housing which is rotation-driven about a rotation axis, and a planetary gear mechanism and a differential gear mechanism which are disposed within the housing, wherein
the planetary gear mechanism includes an inner gear rotatably disposed within the housing with an axis thereof aligned with the rotation axis, a sun gear rotatably disposed within the housing with an axis thereof aligned with the rotation axis and with at least a part thereof inserted in the inner gear, and a planetary gear disposed within the housing such that the planetary gear is rotatable about its own axis, the planetary gear being capable of revolving about the rotation axis together with the housing and engaged with the inner gear and the sun gear, at least a part of the sun gear inserted in the inner gear being provided with a hollow portion, and wherein
the differential gear mechanism includes a hollow casing rotatably disposed within the sun gear about the rotation axis and connected to the sun gear so as to be rotated in unison with the sun gear, an element gear disposed within the casing such that the element gear is rotatable about its own axis, the element gear being capable of revolving about the rotation axis together with the casing, and a pair of side gears rotatably disposed within the casing with axes thereof aligned with the rotation axis and engaged with the element gear.
In the second mode of the present invention, it is accepted that the planetary gear is rotatably received in a pocket formed in the housing or the planetary gear is rotatably supported on the housing through a shaft extending in parallel to the rotation axis. Preferably, bevel gears are used as the element gear and as the side gear, and the element gear is arranged with an axis thereof orthogonal to the rotation axis. Preferably, a tapered chamfering is formed on one end portion of the housing.
A third mode of the present invention relates to a combined differential gear device including a hollow housing which is rotation-driven about a rotation axis, and a planetary gear mechanism and a differential gear mechanism which are disposed within the housing, wherein
the planetary gear mechanism includes an inner gear disposed within the housing with an axis thereof aligned with the rotation axis and rotated in unison with the housing, a sun gear rotatably disposed within the housing with an axis thereof aligned with the rotation axis and with at least a part thereof inserted in the inner gear, a carrier rotatably disposed within the housing with an axis thereof aligned with the rotation axis, and a pair of planetary gears disposed on the carrier such that the planetary gears are rotatable about their own axes, the planetary gears being capable of revolving about the rotation axis in unison with the carrier, the planetary gears being engaged with each other and also engaged with the inner gear and the sun gear, at least a part of the sun gear inserted in the inner gear being provided with a hollow portion, and wherein
the differential gear mechanism includes an element gear disposed within the sun gear such that the element gear is rotatable about its own axis, the element gear being capable of revolving about the rotation axis together with the sun gear, and a pair of side gears rotatably disposed within the sun gear with axes thereof aligned with the rotation axis and engaged with the element gear.
In the third mode of the present invention, it is preferred that the pair of planetary gears are rotatably received in pockets, respectively, which are formed in the carrier. However, it is accepted that the pair of planetary gears are rotatably supported on the carrier through a shaft. Preferably, bevel gears are used as the element gear and as the side gear, and the element gear is arranged with an axis thereof orthogonal to the rotation axis. It is also preferred that a tapered chamfering is formed on one end portion of the housing.
A fourth mode of the present invention relates to a combined differential gear device including a hollow housing which is rotation-driven about a rotation axis, and a planetary gear mechanism and a differential gear mechanism which are disposed within the housing, wherein
the planetary gear mechanism includes an inner gear rotatably disposed within the housing with an axis thereof aligned with the rotation axis and rotated in unison with the housing, a sun gear rotatably disposed within the housing with an axis thereof aligned with the rotation axis and with at least a part thereof inserted in the inner gear, a carrier rotatably disposed within the housing with an axis thereof aligned with the rotation axis and connected to the inner gear so as to be rotated in unison therewith, and a pair of planetary gears disposed on the carrier such that the planetary gears are rotatable about their own axes, the planetary gears being capable of revolving about the rotation axis in unison with the carrier, the planetary gears being engaged with each other and also engaged with the inner gear and the sun gear, at least a part of the sun gear inserted in the inner gear being provided with a hollow portion, and wherein
the portion of the carrier inserted in the sun gear is provided with a hollow portion,
the differential gear mechanism includes an element gear disposed within the carrier such that the element gear is rotatable about its own axis, the element gear being capable of revolving about the rotation axis together with the carrier, and a pair of side gears rotatably disposed within the carrier with axes thereof aligned with the rotation axis and engaged with the element gear.
In the fourth mode of the present invention, it is preferred that a tapered chamfering is formed on one end portion of the housing.